Cross rolling



Aug. 22, 1933. L BECKER 3,923,700

GROSS ROLLING Filed Dec. 10, 1929 2 Sheets-Sheet 1 L. BECKER CROSS ROLLING Aug. 22, 1933.,

Filed Dec. 10, 1929 2 Sheets-Sheet 2 0} IIQYVVENTOR .1 M

Patented Aug. 22, 1933 UNITED STATES PATENT OFFICE CROSS ROLLING Leo Becker, Youngstown; Ohio Application December 10, 1929, Serial No. 413,051, and in Germany December 14, 1928 19 Claims.

10 mandrel. If'the billet being rolled is solid and dependence is placed on the mandrel for piercing the same, this throttling action crushes the metal. It has been estimated that the work of throttling and crushing amounts to from 'to 15 percent of the total work performed. The

work of throttling and crushing is particularly high when a large thick-walled tube is rolled.

I make provision for applying a force directly to the ingot or billet and longitudinally thereof so as to eliminate the necessity for preliminarily throttling to feed the billet forward; This is of particular value when the billet has been preliminarily drilled and no piercing operation is necessary.

By my invention it is possible to enlarge a solid or hollow billet with a resultant tube of desired wall thickness or to reduce a hollow billet to a smaller tube with a power consumption as near as possible to the theoretical minimum. While, of course, the power consumption will depend on the change of size from billet to fin-- ished tube and on the change in wall thickness, I have found that the shape of the cross rolls and the mandrel has a marked bearing on the power consumption.

The shape of the cross rolls heretofore generally employed has been such that the profile of the working surface has been a straight line. I. have found that the profile of the working surface along the line of contact with the metal being worked should be a smooth convex curve and that when such curve is properly designed great power savings may be effected.

I also make provision for adjusting the posion of the cross rolls relative to the billet being worked so as to obtain the best conditions for the work in hand.

In the accompanying drawings illustrating the present preferred embodiment of the invention and certain modifications thereof,

Figure 1 is a diagrammatic view illustrating a pair of cross rolls and a mandrel constructed according to my invention;

Figure 2 is a. view to enlarged scale showing he curvature of .the cross roll profile along the line of contact with the metal being worked,- and also the profile of the mandrel;

Figure 3 is a similar view, but showing a more rapid enlargement of the billet;

Figure 4 is a top plan view of a cross rolling machine; and

Figure 5 is a side elevation thereof.

Figure 1 shows a conventional arrangement of cross rolls 2 having conical heads on shafts 3 and a cooperating mandrel 4. The billet M, which may or may not be pierced, is fed between portion of the the rolls by means of a pusher indicated-generally by the reference character 5.

The profiles of the working faces of the cross rolls 2 and the mandrel 4 are not straight lines, as is common practice, but are curves. This is shown more clearly in Figures 2 and 3.

Referring to Figure 2 and considering the metal at the plane A-A, which is taken perpendicular to the axis a of the billet at the. pointcf the mandrel 4, it will be seen that if this metal'is to be enlarged to the desired size tube without twisting, then a particle of metal a: at the center line A and a particle 11 lying at the surface and radially of the particle :2, must move toward one another as the tube enlarges. The particles :1: and 3 after passing over the mandrel, may be considered as occupying the positions 11:1 and 111. If we take the midpoints Z and Z and connect them by a straight line I, we have the shortest path which the average particle of metal can follow during the cross rolling operation.

This straight line Z is to be considered as the ideal line of the diameters of the rolls and of the mandrel, and it forms the best line from which the curvatures of the mandrel and the cross rolls are figured. If the rate of reduction in cross sectional area from the plane A-A to the plane BB of Figure 2 is figured as constant, the wall thickness of the annulus at any point in the working zone (which lies between the planes AA and BB) may be computed. By measuring inwardly from the ideal line connecting the points Z and Z a distance equal to half this wall thickness and connecting the points thus found, the shape of the mandrel is determinedp Similarly, by measuring outwardly, the profile of the cross rolls is determined. It will be noted that the rolls and the mandrel are convex in profile" If desired, an ideal line maybe drawn by com puting the distance from the axisa of the center of gravity of the section in the plane, AA, and connecting such point with a similarly computed point in the the plane BB; or, if desired,

the radii of gyration may be computed and the ideal line drawn connecting them. In each case it is a characteristic of the rolls and the mandrel that they are convex in cross section, the effect being to do away with excessive working at any one point along the length of the mandrel, and, on the contrary, to distribute the work substantially uniformly therealong. Figure 3 shows a v mandrel for another set of conditions where, as

in Figure 2, both the mandrel and the cross roll are convex.

If the rate of feed imposed by the pusher 5 is equal to the rate of self-feed of the billet (which, in turn, depends upon the oblique position of the rolls), rolling without elongation can be obtained by correct choice of the mandrel. If the self-feed is increased or diminished by changing he oblique position of the rolls without a corresponding change in the rate of feed by the pusher, elongation or shortening of the rolled piece may be produced. The amount of power required will depend on the setting of the rolls. The pusher 5 may be driven by any desired mechanism (not shown), which mechanism should be suitably controlled as to speed so as to vary the amount of feed depending on the speed of the cross rolls. The pusher should be driven from the same source of power as the cross rolls; so that there'will be a certain amount of feed by the pusher per revolution of the cross rolls. If desired, a gear shaft or other variable speed connection may be used to control the rate of feed by the pusher.

It may be desirable in many cases, to control the elongation or shortening by adjusting the pusher feed rate relative to the rate of self-feed, the proper mandrel being used in each case.

If desired, the billet M may be enclosed in part in a tubular guide 6, indicated diagrammatically in Figure 4, to prevent deflection because of the pressure of the pusher 5. If desired, such guide may be mounted in suitable bearings to permit of its rotating with the billet M.

In order to set the rolls correctly so as to obtain the desired rolling conditions and insure the minimum expenditure of power, provision must be made for adjusting the rolls obliquely, tiltably and along their axes. If the rolls are driven by stationary motors and coupling spindles through universal joints, and if the angle of swinging is large, it becomes necessary to divide the angularity of the coupling spindle equally with respect to the driving shaft and the shaft 3 of the cross roll. The arrangement shown in Figures 4 and 5 provides the several adjustments desired, and also automatically positions the coupling spindle properly.

Referring to Figures 4 and 5, one of the cross rolls 2 is shown rotatably mounted in a head '7 having journal bearings 8 and 9 formed therein. The bearing 9 is of a type to prevent longitudinal displacement of the shaft 3 in the head '7. At its rear end the shaft 3 is provided with suitable splines or pods 10 to accommodate a coupling box 11 slidable on the shaft 3. The coupling box 11 is connected to a fixed drive shaft 12 through a spindle 13 making universal joint connections 14 with the shaft 12 and the coupling box 11. At its front end the head '7 is supported on a wedge 15 which, .in turn, rests on a bearing plate 16 fitting over a curved face 1'7 on a base 18. The adjusted position of the wedge 15 is fixed by clamping or locking means of any suitable character, indicated at 15a. By adjusting the wedge 15 .the shaft 3 is tilted upwardly or downwardly.

At its rear end the head 7 is slidably mounted on a rocker plate 19 carried by the base 18.

At its rear end the head 7 is engaged by an adjusting screw 20 carried in an extension 21 of the base 18. By adjusting the screw 20, the entire head 7 may be moved toward or away from the axis a of the billet M, the head sliding .on the wedge plate 15 and the rocker plate 19 during such adjustment.

In order to change the obliquity of the rolls with respect to the axis a, the base 18 is arranged to be swung around, as shown in Figure 4. The base 18 is carried by a sub-base 22 having a curved slot 23 therein. A block 24 moves'in this slot and is bored to receive a pin 25 formed on the underside of the base 18. Any suitabl clamping means may be provided for securing the base 18, in its adjusted position, to the sub-base 22.

At the rear end of the base 18 there is formed a gear segment 26, the teeth of which engage a fixed gear segment 27 on the sub-base 22. As the base 18 is swung, the teeth of the gear segment '26 roll in the teeth of the segment 27, thus properly adjusting the position of the base 18 to insure that the angularity between the axis of the spindle 13 and the axis of the cross roll shaft 3 will be equal to the angularity of the axis between the coupling spindle and the axis of the drive shaft 12. It will benoted that the axis of the pin 25 extends upwardly through the center of one universal joint 14, and that said axis also contains the center from which the pitch line of the gear segment 26 is struck; and fur-' ther, that a vertical axis through the center of the other universal joint contains the center from which the pitch line of thegear segment 27 is struck.

It will "be seen from the foregoing that provision is made for adjusting the cross roll obliquely, axially, or by tilting, as desired, thus making it possible to position it properly for various mandrels and to insure that the power requirements will be a minimum.

I have illustrated and described a present preferred embodiment of the invention. It will be understood, however, that this is by way of illustration only and that the invention is not limited to the form shown but may be otherwise embodied within the scope of the following claims.

I claim:

1. In across rolling machine, a cross roll having a head of generally conical form, the profile of the working surface being a convex curve, and a convexly curved mandrel cooperating therewith, the points connecting the ideal working radius of the mandrel and the cross rolls being a straight line- 2. In a cross rolling machine, a fixed drive shaft, a cross roll, a spindle connecting the cross roll with the drive shaft, and means for adjusting the inclination of the cross rollrelative to the axis of the material being worked, said means being so arrangedthat the angle which the axis of the spindle makes with the cross roll axis in an adjusted position of the cross roll -mid-points of the material thickness before and after rolling.

4. Rolling apparatus for making tubes comprising cross rolls and a mandrel having curved surfaces determined by measurements made from a base line joining the centers of gravity of the half sections of the material before and after passing through the rolls, said measurements being calculated to produce a uniform rate of change in the cross sectional area.

5. Apparatus for rolling including cross rolls and a mandrel convexly curved to produce a decreasing reduction in thickness of the material rolled, the surfaces of said rolls and mandrel being determined from a line joining the extremities of the radii of gyration of the cross sections of the'material before and after rolling.

6. In a cross rolling apparatus, a base, a carriage pivoted thereto for angular movement in a horizontal plane, a cross roll shaft journaled in the carriage, a fixed driving shaft, and a spindle universally connected to the shafts, whereby one set of rollers'is adapted for both expanding and reducing operations.

7. In a cross rolling mill, the combination with a fixed-driving shaft, of an angularly adjustable roll shaft adapted to be driven thereby, an intermediate spindle having universal connection to said shafts, to reduce the angle through which power is transmitted from shaft to shaft, and means for equalizing the angles between the spindle and said shafts.

8. In a cross rolling machine, cross rolls arranged to engage a billet fed through the machine, a mandrel, and means for pushing the billet over the mandrel, the rolls and mandrel having convex surfaces determined from a straight roll line lying in the wall of the frustum engaged by the mandrel and rolls so that the billet is rolled without throttling or crushing.

9. In a cross rolling machine, a cross roll having a profile along the line of contact with the material being worked which is a smooth curve, means for adjusting the angularity of the cross roll axis relative to the axis of the material in one plane, and means for adjusting the obliquity of the roll axis in a vertical plane to the horizontal plane containing the axis of the material.

10. In a cross rolling machine, cross rolls having curved convex surfaces determined from a straight roll line lying in the frustum of 'material in contact with the rolls, and a pusher for the material.

11. In a cross rolling machine, a universally adjustable cross roll having means for adjusting it in a horizontal plane at an angle to the axis of the material to be rolled, means for adjusting the obliquity of the roll axis in a vertical plane, and means for adjusting it toward the axis of the material. a

12. A cross rolling apparatus including cross rolls and a mandrel having their surfaces convexly curved and spaced from a median line in the wall of the frustum of material engaged by the mandrel and rolls, so as to effect a constant rate of change in the material passing therebetween and a decreasing reduction in the thickness of the frustum of material rolled.

13. Apparatus for rolling, comprising a mandrel and cooperating rolls having convex surfaces equidistant from a straight median line connecting the mid-points of the thickness of the wall of the frustum of material engaged by the rolls and mandrel whereby a uniform rate of change of cross sectional area of the frustum Wall along the axial length of the frustum is produced.

14. A rolling mill including a mandrel and cross determined by calculating the distance between roll and mandrel required to produce a constant rate of change of cross sectional area in the material and a decreasing rate of change in the thickness thereof. Q

15. Tube rolling apparatus, comprising cross rolls and a mandrel for cooperatively engaging a hollow frustum of material deformed from a billet, the rolls and mandrel having convex surfaces, all points of which are determined by measurement from a straight'line representing the rolling line between rolls and mandrel and lying within the wall of the rolled frustum, the length and slope of this rolling line being such that the rate of change of cross section along the axis of the frustum is constant throughout the length thereof.

16. In a cross rolling mill, cross rolls and a mandrel provided with convex surfaces for effecting a constant reduction of cross section of the frustum of material between the rolls-and mandrel whereby the wall thickness changes at a decreasing rate, the surfaces of said rolls and mandrel being determined from a straight line joining the extremities of the radii of the gyration of the cross sections of the material before and after engagement with the rolls, said line v constituting the ideal roll line between the rolls and the mandrel.

17. In apparatus for rolling tubes comprising cross rolls and a mandrel having convex surfaces determined from a straight base line connecting the mid-points of the wall thickness of the rolled frustum, the centers of gravity of the half sections of the rolled frustum, the extremities of the radii of gyration of the sections or other like rollline. whereby the cross sectional area'of the frustum varies at a uniform rate and the mandrel outline defines the natural opening within thefrustum.

18. Cross rolling apparatus, comprising a roll mounted on a driving shaft, bearings for supporting said shaft, means for shifting the bearings axially of the shaft. means for adjusting the angularity of the shaft axis to the axis of the material engaged by the roll, and means for adjusting the feeding obliquity of the shaftaxis I to the horizontal'plane containing the material LEO BECKER. 

